pip的问题 Can't connect to HTTPS URL because the SSL module is not available

pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
Could not fetch URL https://pypi.python.org/simple/pip/: There was a problem confirming the ssl certificate: Can't connect to HTTPS URL because the SSL module is not available. - skipping
Could not fetch URL https://www.piwheels.org/simple/pip/: There was a problem confirming the ssl certificate: Can't connect to HTTPS URL because the SSL module is not available. - skipping

报了新的错误：

Could not fetch URL https://pypi.org/simple/xlsxwriter/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.org', port=443): Max retries exceeded with url: /simple/xlsxwriter/ (Caused by SSLError(SSLCertVerificationError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: self signed certificate in certificate chain (_ssl.c:1056)'))) - skipping

研究了好久只知道是证书的错误~按照网上的各种指导尝试了如下方案

1.第一种尝试方式:直接下载get-pip.py文件,执行命令python get-pip.py 结果是:失败

2.第二种尝试方式:加上--trusted-host 执行 pip --trusted-host pypi.python.org install xxx 结果是:失败

3.第三种尝试:发现是url的来源的问题,换成了国内的pip源就可以正常安装了,我使用的是:pip install xlrd -i http://pypi.douban.com/simple --trusted-host pypi.douban.com,结果:失败

1)http://mirrors.aliyun.com/pypi/simple/ 阿里云

2)https://pypi.mirrors.ustc.edu.cn/simple/ 中国科技大学

http://pypi.douban.com/simple/ 豆瓣
https://pypi.tuna.tsinghua.edu.cn/simple/ 清华大学
http://pypi.mirrors.ustc.edu.cn/simple/ 中国科学技术大学

4.第四种尝试:思考了一下混合了两个问题的解决方法，使用命令python -m pip install xlsxwriter --trusted-host=pypi.python.org --trusted-host=pypi.org --trusted-host=files.pythonhosted.org ，结果：成功